The concentration of potassium is higher in red blood cells than in the surrounding blood plasma. This higher concentration is maintained by the process of*

Human genetic material is represented in the diagram below.

The region labeled A is made up of a section of*

Brothers and sisters often have similar facial characteristics, such as nose shape or eye color, because they*

Compared to a normal body cell, a normal egg cell contains*

The variations that exist in a population of wild giraffes are usually a result of events that occur during*

Evidence that best supports the theory of biological evolution was obtained from the*

The human immune system fights infection by releasing*

The function of a specific enzyme is most directly influenced by its*

A vaccine for the viral disease known as chicken pox would contain*

Which process will result in a gain of energy in an ecosystem?*

A photograph of a polar bear in its environment is shown below.

One possible reason why polar bears might not be able to survive if the environment they live in changes is because*

An ecological process is represented below.

Which statement describes an event in this process?*

An infection in the body might result in a sudden*

Which disorder could develop in the human body when the immune system attacks a usually harmless environmental substance?*

In the human body, carbon monoxide reduces the amount of oxygen that can be transported to cells. Breathing in too much carbon monoxide will most likely result in the production of*